The present invention relates to leg rests for wheelchairs. In particular, the present invention relates to wheelchair leg rests that automatically extend in length when being elevated.
Conventional wheelchairs typically have leg rests that can be pivoted upwardly to a substantially horizontal disposition. The ability to raise the leg rests is important, for example, because it often is desirable for therapeutic reasons to be able to elevate the patient's foot from time to time.
In conventional wheelchair structures, the leg rest is pivotally connected at its upper end to the wheelchair frame adjacent the front edge of the seat bottom, and a foot rest is located at the lower end of the leg rest. The foot rest normally is mounted on a shaft that is inserted into the lower end of the leg rest and secured by a clamp. The shaft telescopes within the leg rest to enable the location of the foot rest to be adjusted to a position that supports the patient's foot when the patient's leg is in the normal, lowered position.
Because the pivot point of a conventional leg rest does not coincide with the pivot point of the knee of the patient seated in the wheelchair, the foot rest tends to push upwardly on the bottom of the patient's foot when the leg rest is elevated. As a result, raising the leg rest exerts unwanted compression on the patient's knee and/or causes the knee to be lifted.
A number of attempts have been made to compensate for the eccentricity between the knee joint and the conventional wheelchair leg rest. In the structure shown in U.S. Pat. No. 3,072,437, for example, the leg rest assembly is connected to the wheelchair through a pair of horizontally telescoping struts, which enable the entire leg rest to be translated horizontally away from the wheelchair when the leg rest is raised. The horizontal movement of the leg rest assembly, however, is accomplished by the patient's foot forcing the assembly to move away from the wheelchair as the leg rest is being raised. For certain patients this exerts unwanted pressure on the leg.
In another attempt, shown in U.S. Pat. No. 4,486,048, the leg rest is a telescoping strut pivoting about a leg rest pivot located on a horizontal mounting arm. An actuating lever is connected between the lower member of the strut and a second pivot point disposed on the mounting arm forwardly from the leg rest pivot. Raising the leg rest causes the lower strut member to extend automatically. Although this mechanism operates without exerting unwanted pressure on the patient's leg, the positioning of its actuating lever near the pivot point for the leg rest creates a potential safety hazard. When the leg rest is in the lowered position, the leg rest, actuating lever, and mounting arm form an open triangle. When the leg rest is raised, the triangle closes as the angle between the mounting arm and actuating lever approaches zero. At the least, the patient's clothing can get caught in the closing triangle. More importantly, the actuating structure can pinch the skin or catch the fingers of the patient or attendant as the leg rest is being raised.
The present invention is intended to provide an improved wheelchair leg rest that extends automatically when raised.
The present invention is intended to provide a wheelchair leg rest that extends automatically when raised while minimizing the risk of clothing or hands becoming caught in the extending mechanism.
Additional advantages of the present invention will be set forth in part in the description that follows, and in part will be obvious from that description or can be learned by practice of the invention. The advantages of the invention can be realized and obtained by the apparatus particularly pointed out in the appended claims.